Mounting for dynamo-electric machines



July 14, 1 936. H; ASWTH E AL 2,047,838

MOUNTING FOR DYNAMO-ELECTRIC MACHINES I Fi1 ed Sept. 20, 1955 Inventor Henry A.Smith, Claude NLSummePs,

His Attorney.

- Our inventionis shown .as appligg to a; iiyhamo idilnhivehtidu';

3 ifiannullis offlnsulatingsematerialr'suppbrted a.

metal band and prov dedaswi hzeslqq ricalll duc lveh h ure i fi en It of our present invention, which applQcgtion lgizee 1 t 55 be regarded as prior art with respect to this application.

This type of mounting arrangement is readily adaptable to various applications, such as motor driven washing machine agitators, mechanical refrigerating apparatus, etc., which maybe driven by a belt 3| having a frictional driving connection with a driving pulley 31 mounted upon the dynamo-electric machine shaft IS. The friction of such a driving connection may generate suflicient static electricity to cause undesirable static discharges between the dynamo-electric machin and ground. 1

In accordance with our invention, the accumulation of a static electric charge upon the insulated dynamo-electric machine isprevented by arranging an electrically conductive element 33 in contact with the metallic hub I and the metallic band 20. This electrically conductive element is preferably formed of a high resistance material. It would be undesirable to utilize a low resistance ground connection between a dynamo-electric machine and its mounting, as this.

would introduce the possible hazard of a serious ground in the dynamo-electric machine circuit if part of the electrical circuit of the dynamoelectric machine should become grounded. Wehave determined experimentally that a resistance of eighty megohms is sufliciently low to pre-- vent the accumulation of a static charge upon the dynamo-electric machine and that a resistance of one megohm is sufficiently high to eliminate any sensation of shock from an average low voltage distribution line of approximately 110 volts. Therefore, in order to eliminate the static charge, and at the same time prevent the hazard of an average line voltage shock to ground, it is desirable to introduce an electrically conducting path of from one to eighty megohms between the insulated dynamo-electric machine and ground.

Various arrangements and materials can be utilized for providing such a conducting path.

We prefer to use a strip 33 of fibrous material, such as asbestos cloth, impregnated with an electrically high resistance conductive material, such; as graphite or lead peroxide. In the preferred embodiment of our invention, the annuluses H are formed of molded resilient rubber bonded to the metallic band 2! and an electrically conductive element 33 is molded in the rubber annuluses. so as to extend beyond the inner surface thereof. through the rubber annuluses, and into electrical contact with the metallic band 20, as indicated at 34 in Fig. 3. The annuluses H are fitted on the hub 14 by aligning the projections 18 with the notches l5 and pressing the annuluses into position. When thus mounted, the inner end 0! the electrically conductive element 33 forms a good electrical contact with the metallic hub l4 and the electrical potential is equalized between the metallic elements in contact with the inner and outer surfaces of the insulating annuluses ll.

While we have illustrated and described one embodiment of our invention, modifications thereof will occur to those skilled in the art. We desire it to be understood, therefore, that our invention is not to be limited to the particular arrangement disclosed and we intend, in the appended claims, to cover all modifications which do not depart from the spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent in the United States B;

in: a rotatable memberand a stationary member of electrically conductive material, a resilient member of electrically insulating material surrounding at least a portion of said stationary member, an electrically conductive support for said resilient member, and means including an electrically conductive element carried by said resilientmember between the inner and outersurfaces thereof for equalizing the electrical potential between said surfaces.

2. A dynamo-electric machine or the like including a rotatable member and a stationary member of electrically conductive material, a member of resilient insulating material surrounding at least a portion of said stationary member, means including an electrically conductive support for said resilient insulating member, and means including an electrically conductive high resistance element extending through said resilient insulating materialbetween the inner and outer surfaces thereot for equalizing the electrical potential between said. surfaces.

3. A dynamo-electric machine. or the like in-- eluding a rotatable member and a stationary member of electrically conductive material, a member of resilient rubber surrounding at least a portion of said stationary member, an electrically conductive support for said resilient rubber member, and means including an electrically con.-

ductivehigh resistance element molded in said resilient rubber member and extending into contact with said stationary member and said electrically conductive support for equalizing the electrical potentialtherebetween.

4-. A. dynamo-electric machine or the like including a rotatable member and a stationary member of electrically conductive material, a member of resilient rubber surrounding at least a portion ofsaid stationary member, an electrically conductive support for said resilient rubber member, and means including a strip of fibrous material impregnated with electrically conductive material and extending into contact with said stationary member and said electrically conductive supportfor equalizing the electrical potential therebetween.

5. A memo-electric machine or the like including a rotatable member and a stationary member of electrically conductive material, a

member of resilient rubber surrounding at least cally conductive support for said resilientrub-- ber member, and means including an asbestos cloth strip impregnated with lead peroxide extending between the inner and outer surfaces of said resilient rubber member and in contact with said stationary member and said electrically conductive support for equalizing the electrical potential therebetween.

"I. A dynamo-electric machine or the like having] rotatable member provided with a shaft and astationary member of electrically conductive material, a frictional driving connection mounted fer: are shaft, a resilient member of electrically f insulating material surrounding tion of said stationary member, conductive support for said resilient member, 'means including an electrically conductive material carried by at least a poran electrically said resilient member for equalizing the electrical potential between said etat ionarymember and said electrically conductive support.

8. A dynamo-electric machine'or the likehav- 1 ing a rotatable member provided with ashaft and astationary member provided with a hub of elecp1 "trically conductive material extendingabout said shaft, a frictional driving connection mounted on said shaft, prising an "said hub, a metal bandsecured to the outer surface of said rubber annulus, and fling an asbestos cloth strip peroxide extending, beyond a mounting for said-machine comannulus of resilient rubber fitted on means includimpregnated with lead said rubber annulus andtherethrough into elec- V trical. contact with said metal band and said hub for equalizing the electrical potential therebeftweenr 9. A dynamo-electric machine or the like hairring a rotatable member provided with a shaft 7, q, and a stationary member provided with a hub ofv I electrically conductive material extending about' said shaft, said hub fnotchesand a circumferential frictional driving shaft, a mounting having axially extendin groove therein, a connection mounted on said for said 'machine'comprising I an annulus of resilient rubber having complementary I Qtween, a support said metal band, and means. incl engaging-said support for holding said portions on outer surface of said having an openend engaging a' clamp metal hand against rotation. 1

arranged to contact the innersurface of,

the inner surface thereof arranged to engage said notches and said groove, a metal band secured to the I annulus and having spaced ends, means including an asbestos strip impregnated with graphite extending through said resilient rubber into electrical contact with said hub and said'metal band; for equalizing the electrical potential therebe electrical potential between the 10. A mounting member for a dynamo-electric 4 machine or the like of resilient insulating maelectrically conductive members, and means ineluding a strip of fibrous material impregnated with electrically conductive high resistance material extending between the sides thereof and members for equalizing the electrical potential therebetween.

12.A mounting member of molded insulating material having sides-formed and arranged to be secured between electrically conductive membrs, and, means including an electrically c'onductive high resistance member molded in said insulating material and extending between'said sides and beyond one of said sides for equalizing the electrical potential on opposite sides'of said i insulating material.

13. A mounting member of resilient rubber formed and arranged to be secured between electrically conductive members, and means including an asbestos cloth ,strip impregnated with lead peroxide extending through said resilient rubber between the sides thereof for equalizing the electrically conductive members. I

14;. A mounting member of resilient rubber formed and arranged to be secured between electrically' conductive members, and meansincluding a fibrous element impregnated with graphite the electrically conductive extending through said resilient rubber for equalv izing the electrical potential on opposite sides of said resilient rubber member.

- HENRY A. SMITH.

CLAUDE M. SW. 

